The present invention relates to a pedestal mount capacitive pressure sensor used primarily for sensing air pressures in air vehicle operations which is constructed to provide long-term stability, reduce temperature-induced errors and to provide a rugged, accurate pressure sensor assembly.
Solid-state capacitive type pressure sensors have been well-known in the art, and are widely accepted because of their ability to be miniaturized, and to be made using batch fabricating techniques to hold costs down. Such prior art sensors have used glass or semiconductor bases and formed diaphragm layers joined together around the rim of the diaphragm with anodic bonding, glass frit layers, metal diffusion and similar bonding techniques.
It also has been known in the art to metalize borosilicate glass (Pyrex) layers for forming capacitive electrodes for use with deflecting semiconductor diaphragms. Temperature stability is a problem for pressure sensors used in air vehicles because they are subject to wide, quite sudden swings in temperature. Temperature induced stresses caused by materials which have different temperature coefficients continues to be a problem, and stress isolation between the outer housing and the sensor die package is also necessary.